Generally, tunnel light fixtures are not only frequently exposed to great amounts of eddy current caused by vehicles traveling through a tunnel, but are also likely to be corroded due to various emissions. In particular, a coupled part of the light fixture suffers from severe corrosion due to use of calcium chloride and the like in winter. Conventionally, the tunnel light fixture is provided with a separate hinge-coupling mechanism to couple a body and a cover in combination with separate bolts and nuts, which are used to fasten the body and the cover through bolt holes formed in the body and cover. Therefore, the conventional tunnel light fixture requires not only individual fastening of the bolts and nuts through the bolt holes of the body and cover, but also a sealing operation with respect to the bolt holes and the like, causing an extended installation time. Furthermore, in the event where the hinge-coupling mechanism is corroded and separated from the light fixture, there is the possibility of serious traffic accident.
Moreover, since a lighting lamp in the tunnel light fixture is turned on day and night for a long period, air at high temperatures is likely to generate in the tunnel light fixture and noticeably reduces the lifetime of a ballast and the like, thereby causing frequent replacement and failure of the ballast and the like.
Furthermore, since the tunnel light fixture is generally installed in a humid and dusty environment, dust is likely to be attached to inner and outer surfaces of the light fixture and causes reduction in the cleaning cycle along with frequent failure, thereby providing a problem of requiring a further thorough sealing operation.
In a tunnel light fixture disclosed in Korean Patent Laid-open No. 2001-0103802, although a hinge-coupling mechanism for the light fixture is partially improved, a separate hinge-coupling mechanism is still required. In a tunnel light fixture disclosed in Korean Utility Model Registration No. 0377203, although a plurality of protrusions are formed on the body and cover to increase a cross-sectional area for heat dissipation, the cross-sectional area for heat dissipation increases slightly so that the heat dissipation is insufficient, thereby failing to maintain the lifetimes of other components. In a tunnel light fixture disclosed in Korean Utility Model Registration No. 20-0313767, a diaphragm is disposed to prevent heat of the lamp from being transferred to the ballast and other components, and a double-rubber packing is disposed along a rim of the body to improve sealing. However, since the diaphragm is coupled to the body through screw holes in the bottom of the body in a state of being separated a predetermined distance from the bottom of the body, and since the body faces upward in the light fixture and so heat is directed upward, there is still a problem in that most of the heat from the lamp is transferred to the ballast and the other components through a gap between the bottom of the body and the diaphragm. Since a recess is insufficiently formed on the body of the light fixture, the light fixture suffers from a problem in that the double-rubber packing is likely to slip from the body. In this case, although an existing wide rubber packing has stability in the light fixture, the existing wide rubber packing has a problem in that, since the existing wide rubber packing is located higher than the rim of the body in a packed state, it is likely to slip to the side of the body under compression of the cover.